Circuit breaker



Dec. 29, 1953 H. v. ELLIOTT 2,664,480

. CIRCUIT BREAKER Filed March '7, 1950 Patented Dec. 29, 1953 Harold V.- Elliott, Anderson;

Ind aissignor to General Motors Corporation}- Detroit, Michaa corporation. of Delaware Application March 7, 1950,'.Serlal No; 148.172 6: Clams;- (01. 21102-116)" This invention relates to im rovemefitsme1ec-- tric circuit breakers and more particularly to circuit breakers having means whereby the de vice will be automatically operated in event" an excess amount of current is passed through the circuit controlled by the circuit breaker; A

An object of the present invention is to providean improved electrical device-which will act as a thermostatic circuit breaker and one that will not burn out or be made useless when operated, but may be restored to circuit closing position and repeatedly reused.

Another'object' of the present invention is to provide an improved thermostatic circuit breaker which is' constructed to provide a snap action in breaking the circuit and whichrequi'res-manual resetting on order to again close the circuit.

Another object of the present invention is to providea thermostatic circuit breaker'which will have-nearly constant contact pressure up to the time of separation of the contacts and when the contacts separate they will separate with a snap action, thus eliminating arcs and consequently burning of the contactsurfaces:

Another object of the present" invention" i's-to provide an improved: circuit breaker including a resilient conducting member and a'- bimetallic member which are constructed to provide integral contact portions and latch sections so that the contact portions of both members are large in relation to the latch sections to' assure that most of the. current passing through the members will'take the path of least resistancewhich is: through the contact portions of therespective members.

Further objects and advantages'of the present invention will be apparent from" the following: description reference being. bad to the: accent panying drawings wherein a preferred embodiment of the: present invention is. clearly. shown.

Inthe drawings:

Figs. 1 and 2 are: top and bottomplan vie-ws; respectively of the switch embodylngthe present invention.

Fig. 3 is a top plan view of theiswitchshown in Fig. 1 with the cover removed anddra'wxionan enlarged scale.

Fig. 4 is aside view looking; in the direction: of arrow l of Fig. 3.

Fig. 5 is a sectional view taken on lines-5 of Fig. 3 but drawn to the same scale ofl Fig;-3 and showing the-switch in its openp'osition;-

Fig; 6 is asectional. view'taken; substantially on lines 6-6 of Fig. 3 showing one form-of mounting parts to a support;

neath ancl'in' physical contact Fig? 7" is a sectional view showing a modified construction and arrangement of parts of the invention.

Referring-tothedrawings 2D designates a base or supporting block ofsuitable insulating ma provide'ahas'e portion having an ear 25 at its free end'which is bent at an angle. The other end of baseportionfl is bent upwardly to provide a yokeZB andthen inwardly to provide an arm 21- which-overlies'the base. The arm 21 is slotted-at 28 to provide prongs on legs serving as a contact portion 30- and a-latch section 29. The latch section 2 94s slightly longer than contact portiorr 3'0, but portion- 30- is much greater in area than section 29. Both prongs in their normal state are inclined inwardly from the yoke 26, as shown in Fig. 5. The prong 29 has a greater incline" than prong 30 to be described. The base portion 24 of 'the spring conductor 22 issecured' to the support 20 by suitable fastening means, such as a rivet 3l. The rivet 3| also secures a plate 32' to the underside of the base so asto provide one'terminal plate for the switch for making connection to a lead (not shown) of the" circuit to be controlled by the switch. If desired; the terminal 32 could be placed underwith the base portion-2'4; The ear 25 extends downwardly into one end of an elongated slot 33 formed in the base 2 0" and cooperates with the side walls of theslot to prevent the conductor 22 from turningrelative to the b'ase' 2.0.

The base 26 also supports a u shaped bimetal element'or strip 35 having arms 36 and 3'! and a yoke 38 The arm3'5 is provided with an ear 39 which extends'into' the other end of the slot 33 to prevent the element 35" from turning relative to the block 20'. The U-shaped member is con structed of thermostatic or bimetallic metal which is more sensitive to' heat when overloaded by electrical current passing therethrough than the other elements ofsuch a circuit. This element undergoes distortiontwhen soheated by an overload of electrical. current passing through it. Tlieiyoke' 38 is partly shearedv from its upper. end to provide a stop or latch section 40. The sheared-portion is bent inwardly out of'the plane In the present instance the base is of the yoke 38 to provide an inclined surface. The arm 31 is greater in width than the stop Q8 and is so positioned that it will overlie the free end of arm of spring member 22. The free end of prong 30 carries a contact 4| while the free end of arm 31 carries a contact 42. The arm 36 is secured to the base 20 by a rivet cm which also secures a plate 44 to the underside of the base. The plate provides a terminal for the switch for making connection to a lead, not shown, of the circuit to be controlled by the switch.

A plunger or actuator 50 of insulating material, such as molded Bakelite, has a head 5| and a shank 52 provided with a flat side. The shank has a sliding fit through an opening 53 having the same contour as the shank, thus the plunger is kept from turning relative to the base. The upper side of the head El is provided with spaced lugs 54 which are so positioned that each lug will be located under one of the arms 29 of the conducting members 22.

When a circuit to be controlled is in its open position the switch parts assume approximately the positions shown in Fig. 5 wherein the free end of the arm 29 is free of the stop or latch section and the contacts Al, 42 are separated. When it is desired to close the circuit, the operator pushes the plunger upwardly, as viewed in Fig. i, from the position shown in full lines to that position shown in dot-and-dash lines. When the plunger is actuated to close the switch the lug 55 will engage the latch section or arm 29. As the arm 27 is moved upwardly a short distance its free end 29a will engage the sloping surface of the latch section 60 and the contact 41 will engage contact i2. Further upward movement of arm is will cause both arms 25, 3D to bend into a concave formation to increase the internal stresses in the arms. As the free end 2911 moves upwardly it urges the yoke 38 outwardly to increase the ir ternal stresses therein. This outward movement of the yoke 33 causes the contacts M, 2 to move relative to each other to produce a wiping act-ion therebetween, thus any foreign matter which tends to interfere with good contact engagement will be wiped away. As soon as the free end 2% is above the latch section the increased stresses in the element will cause the yoke to snap back under the end 29a. Upon release of the actuator the arms 29, 38 move rapidly toward their normal position but the latch section will arrest the arm 29 and the engagement of the contacts is assured. When the arm engages the latch section the arms 29 and 36 will maintain their concave formations and the internal stresses in the arms will resiliently hold contact 42 against contact l with a continuing pressure, insuring a continuous pressure electrical connection therebetween up to the time of separation. The spring arm 29 is the primary motive force in opening the contacts with a snap action as it is not greatly involved in an overload. in the load circuit. This is due to the fact that the conductor 22 and the bimetallic element are so constructed that the contact portions of both the spring conductor and the bimetallic element are large in relation to the latch sections. Therefore, most of the current will take the path of least resistance and flow through the contact portion of the respective parts.

The structure as described is adapted to be placed in a circuit and will complete a circuit from the terminal 32 through rivet 3|, conductor 22, contacts 1H, 42, thermal element 35, rivet 3m and plate 44. The bimetal member is so selected that when a predetermined overload of current flows through circuit the bimetal will be distorted to the left as viewed in Fig. 4 a sufficient distance to move the latch section 46 beyond the free end 290. of arm 29 whereupon the circuit will be broken with a snap action and it will remain in open position. As soon as the circuit is opened the bimetal strip begins to cool and returns to its normal position without engaging any portion or" the conductor member 22.

The drawing shows the switches enclosed within a cup-shaped cover 60 having its open end resting on a peripheral shoulder 8| provided by the base 20. The cover has tangs 62 which fit through notches 63 and these tangs are bent over, as at 64, against the under side of the base to hold the cover in position on the base.

In Fig. '7 a modified form of construction for the base portion 24 of the conductor 22 is shown. In this form the leg base portion 2 3 is bent outwardly, instead of inwardly as shown in Fig. 6. In this instance, the ear formed on the end of base portion 24 will extend into a recess I33 to prevent the conductor 22 from turning relative to the base. When this form is used for the conductor 22, a similar construction could be made to the thermal element 35.

While the embodiments of the present invention as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

I. In a switch the combination with a base provided with two terminals; of a thermal-responsive means having one portion secured to one of said terminals and another portion split to provide a detent and a support for a contact element; a movable member having one portion secured to the other terminal and having a split portion providing two resilient arms one of which carries a contact element operative to engage the first mentioned contact element, the other arm providing a latch engagement with the detent to hold the contact elements in engagement, said latch being releasable by the detent to discontinue contact engagement in response to flexing of the thermo-responsive means; and an actuator engaging the latch arm, said actuator being operative to flex the movable member for contact ongagement.

2. In a switch the combination with a base provided with a plurality of terminals; a thermoresponsive means having one portion secured to the base and electrically connected to one of the terminals and another switch portion bifurcated to provide a detent and a support for a contact element, a movable switch element having arms, one of which is electrically connected to the other terminal, the other arm being bifurcated and providing two flexible portions one of which carries a contact adapted to cooperate with said contact element, the other providing a latch portion adapted to engage the detent for retaining the contact and element in engagement, said thermoresponsive means flexing in response to a predetermined current flow therethrough to release the latch and separate the contact elements; and an actuator for said other switch portion, operative to move said portion for contact engagement.

3. In a switch the combination with a base pr vided with terminals; of a one-piece bimetalmember having one portion electrically connected with one of said terminals and another portion split to provide a shoulder and a support for a contact; a one-piece movable member having one portion electrically connected to the other terminal and having a split portion providing resilient arms one of which carries a contact operative to engage the first mentioned contact, the other arm providing a latch engageable with the shoulder to hold the contacts in engagement, said latch being releasable by the shoulder to discontinue contact engagement in response to flexing of the bi-metallic element; and a plunger for engaging the latch arm, said actuator being operative to fiex the movable member for contact engagement.

4. In a switch the combination with a base provided with a plurality of terminals; a U-shaped lei-metallic member having one leg electrically connected with one of the terminals, and having a yoke split to provide a latch section and having the other leg serving as a contact element; a one-piece U-shaped metallic member having one leg electrically connected with another terminal and having the other leg split providing resilient arms one of which serves as a contact element, the other arm providing a latch engageable with the latch section to hold the contact elements in engagement, said latch being releasable by the latch section to discontinue contact engagement of the elements in response to flexing of the bi-metallic member; and an actuator for engaging the latch arm, said actuator being operative to flex the movable member to cause engagement between the contact elements.

5. In a switch the combination with a base provided with two terminals; of two oppositely disposed unitary contact carriers, one of which is bi-metal attached to one of the terminals and having a split portion forming a contact arm and a stop, the other being flexible and secured to the other terminal, and having a split portion forming a second contact arm including a latch engageable with the stop when said other contact carrier is actuated to cause engagements of the contact arms; and an actuator for said latch.

6. In an automatic circuit breaker having a base of insulating material; a pair of binding posts supported thereby to which the conducting elements of a circuit controlled by said circuit breaker are adapted to be connected; a one-piece temperature responsive means connected to one of the posts, said means being so constructed as to provide a stop and a contact portion; a onepiece resilient conducting member connected to the other post, said member including a contact portion and latch portion tending to move to a circuit open position, said latch portion normally held in latch position with the stop to hold the contact portion in engagement with the contact portion of said temperature responsive means, said temperature responsive means being operable to release the latch portion from the stop and permit separation of said contact portions and opening of the circuit when a predetermined circuit temperature is reached, and a manually operable resetting member movably supported in said base, said member being movable when actuated to a position to move the latch portion of said resilient conducting member to its latched position in order to reclose the circuit when the circuit temperature falls below a predetermined degree.

HAROLD V. ELLIOTT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,431,220 Donle Oct. 10, 1922 2,191,588 Sattler Feb. 27, 1940 2,458,804 Sundt Jan. 11, 1949 2,490,320 Pashby Dec. 6, 1949 2,491,032 Burke Dec. 13, 1949 

